Thermoelectric generator



July 10, 1928. 1,677,029

T. s. FULLER ETALY THERMOELECTRIC GENERATOR Filed Nov; 27, 1925 *2? lllllllllll a 2 I a s I I a I e I I I 5 i I 7 Inventors Truman S. Fuller Nathan H. Adams, Frank G. Nolte.

air Attor-nqg 7 Patented July 10, 1928.

TRUMAN S. FULLER, NATHAN H. ADAMS, AND FRANK G. NOLTE, OF SCHENECTADY, NEW YORK, ASSIGNORS TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

THERMOELECTRIO GENERATOR.

Application filed November 27, 1925. Serial No. 71,827.

Our present invention relates to improvements in the construction of thermo-electric generators and more particularly to thermoelectric generators employing flames for supplying heat to the hot junctions of the thermo-couples comprising the generator.

It is an object of our invention to provide a device of the above type which shall be adapted to supply current at a substantially constant voltage to small electrical apparatus such as the space current devices employed in radio broadcast reception.

In carrying our invention into effect, we employ a thermopile which is fabrlcated 1n a manner similar to that illustrated in the copending application of Nathan H. Adams, Serial No. 19,732, filed March 31, 1925. In the present application that portion of the thermopile which includes the junctions to be heated comprises a rectangular portion of reduced cross section which projects from the end of the thermopile. A burner adapted to employ either gas or gasoline as fuel is mounted on the thermopile adjacent the projecting portion thereof. The burner comprises two tubular portions which extend lengthwise on opposite sides of the thermopile. Each portion is provided either with a single opening which extends lengthwise of the tubular portions or with numerous small openings instead of the single opening. The flame is directed from the burner upon opposite sides of the hot junctions of the thermopile so that the junctions are heated evenly and in an eflicient manner. The opposite end of the thermopile is provided with a series of cooling plates, comprising a radiator, in close thermal contact with the cold junctions of the thermopile. The radiator encloses the cold junctions and extends towards the hot junctions a distance equal to approximately one quarter of the height of the thermopile. The radiator is mounted between a pair of supporting brackets which extend upwardly and are attached at their upper ends to the burner member. In this manner the thermopile is rigidlyheld between the burner and radiator.

The novel features which we believe to be characteristic of our invention are set forth with particularity in the appended claims.

Our invention itself, however, both as to its organization and method of operation will best be understood by reference to the following specification taken in connection with the accompanying drawing in which Fig. 1 shows a perspective view of the thermo-electric generator; Fig. 2 is a cross-section of the thermo-electric generator; Fig. 3 is an exploded perspective View of the thermopile, metal holder and insulator; Fig. 4 is an enlarged detail view showing the electrical connection between the end of the thermopile and one of the binding posts on an end bracket.

Referring to the drawing, we have indicated at 1 a thermopile comprising a plurality of substantially parallel, unlike, metal plates united at their ends to form a series of thermocouples. The end of the thermopile which includes the junctions to be heated is reduced in cross section to provide a v relatively thin projecting portion 2 and a pair of shoulders 3. Adjacent the hot junctions, the thermopile is surrounded by a thin metal band 4 which is insulated from the thermopile by mica insulating strips 5. The other end of the thermopile is placed in .a relatively thin metal cup 6 and insulated from the sides and bottom thereof by mica orsimilar insulators 7 and 8. The thermopile fits snugly within the metal cup 6 so as to be in good thermal contact therewith. Cup 6 is-provided with openings 9 in the bottom thereof and adjacent each end through which electrical connectors 10 and 11 may extend.

The thermopile is mounted on a plurality of flat substantially parallel metal cooling plates 12, which may be made of aluminum or copper, or any suitable material desired. Each plate is provided with a notch 13 of sufficient width to snugly accommodate the thermopile and its associated metal cup 6.

The radiator is mounted between a pair of brackets 11 to which it may be permanently conectecl by means of a plurality of bolts and nuts 15 and 16. Each bracket 14 is provided with an extension, not shown, to which a heater element or burner 17 may be permanently connected by means of bolts 18.

The burner comprises a pair of tubular members 19 and 20, each of which is promembers 19 are bolted together at one end,

as indicated at 25. The flanged portions 22 of the tubular members are each bolted to plates 26 and 27, which in turn are bolted to the brackets 14, as indicated at 18. The openings 21 should be spaced from the reduced 'end 2 of thethermopile a distance sufficient to ensure that complete combustion will take place at the surface of the reduced portion. If the openings 21 are spaced too far away from the reduced end combustion will take place before reaching the reduced portion, while if the openings are too close to the hot junctions combustion will take place above the reduced portion.

If gasoline is to be employed as fuel, a gas generator 28 may be employed. The gas generator comprises a pipe 29 supported on a. pair of brackets 30 and 31 and provided with a valve and an inlet pipe 32. A handle 33 is employed to vary the valve opening at the end of the generator adjacent pipe 24. In starting the generator, gasoline placed in a receptacle 34, which is connected to flanges 22, as indicated at 34, first is ignited. The heat from the burning gasoline vaporizes the gasoline in generator 28 and thereafter the gas which issues from openings 21- in the tubular members may be ignited.

The burner 17 is supported on shoulders 3 of the thermopile 1, and is insulated therefrom by thin mica strips 35. In this manner the thermopile is rigidly held between the radiator and the burner 17 so that movement of the thermopile relative to either the radiator or the burner is prevented.

Each bracket 14 is provided with a rest or recessed portion 36 on which is mounted a binding post 37 adapted to be connected to one end of the thermopile by means of connector 10 or 11, which passes through the opening in the bottom of cup member 6.

If the fuel employed is illuminating gas, the generator 28 and starting device 34; may be omitted and the gas supply connected directly to chamber 23. l In providing the reduced portion which includes the hot-junctionsof the thermopile, it is necessary of course to consider the total internal resistance of the thermopile since a thermo-electric generator operates at its highest efficiency when the internal resistance of the generator is substantially equal to the external resistance of the load circuit supplied by the generator. In the present case the reduced portion is so proportionedthat it has a relatively small cross section compared to the heat receiving surface, and,

junctions to be heated being reduced in cross section, a shoulder on said thermopile, and a heater comprising an elongated tubular portion mounted on said shoulder, said tubular portion having a burner opening adjacent the reduced portion.

3. In combination, a thermopile, the portion of said thermopile which includes the junctions to be heated being reduced in cross section, and means for heating said reduced portion, said means including a pair of tubular members provided with burner openings and mounted on said thermopile and on opposite sides of said reduced portion.

4:. In combination, a thermopile, a heater" adapted to cooperate with the junctions to be heated and a radiator adapted tocooperate with the-cold junctions of the therm0- pile, means for supporting the thermopile on the radiator, and supporting means connected to said radiator and heater.

5. In combination, a thermopile comprising a plurality of substantially parallel sheets of unlike metal forming thermo-el'ectric couples, said sheets being united at opposite ends thereof to form an integral zigzag strip and a radiator cooperating with said thermopile, said radiator comprising a plurality of substantially parallel cooling plates, each of said plates being provided with a notched portion adapted to accommodate said thermopile, the cooling plates being arranged in planes substantially parallel to the elements of the thermopile.

6. In combination, a thermopile comprising a plurality of substantially parallel sheets of unlike metal, said thermopile being substantially rectangular in cross section, a plurality of cooling plates supporting said thermopile, said plates being arranged in planes substantially parallel with the planes containing the elements of the thermopile, and supporting brackets connected to said cooling plates at opposite ends of the thermopile.

7. In combination, a thermopile, a plurality of cooling plates associated with and supporting the thermopile, a pair of supporting brackets connected to said cooling cluding means arranged substantially at right. angles to the direction of said flames 10 for conducting hot gases away from the thermopile.

In Witness whereof, We have hereunto set our hands this 25th day of November, 1925.

TRUMAN S. FULLER. NATHAN H. ADAMS. FRANK G. NOLTE. 

